Uniformly surfacing flat metal bodies



Nov. 9, 1943. JOHNSON 2,333,936

UNIFORMLY SURFACING FLAT METAL BODIES Filed March 28, 1942 I 2Sheets-Sheet l f H ---i: J4 I; A "iii 1 'AAdFd k 1 J JEII F4 V f/ 1-9::1L

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Patented Nov. 9, 1943 UNITED STATES PATENT OFFICE UNIFORMLY svnmcmc FLATMETAL BODIES Raymond Johnson, Westmoreland. County, Pa.. assignor toCarnegie-Illinois Steel Corporation. a corporation of New JerseyApplication March 28, 1942, Serial N 0. 436,693

11 Claims.

finish presents an absolutely uniform appearnace into which steam wasadmitted until the desired uniformity of color was produced.

Gradually there ensued a technical transition from hot rolled productsto cold rolled products, but it was found that this same practice, whenapplied to cold rolled sheets, did notaflord the acquisition of auniform blue oxide coating due to the inherent flatness and high surfacefinish of the cold rolled sheets, which caused the adjacent surfaces ofthe sheets in a stack intimately to engage, and thus to exclude theactive oxidizing atmosphere.

It is the primary object of the present invention to teach a method forpretreating cold reduced sheets preparatory to a surface treatmentthereof in stacks, such as a steam bluing operation. In a preferredembodiment of the invention, such sheets are singly passed through acorrugating or crimping device to impart a gentle undulation to thesurface thereof so that when they are stacked together, the undulationsdo not nest but maintain the sheets in spaced relationship throughoutthe major portion of their surface areas. This allows for theinter-penetration of the active atmosphere during the annealing orSurfacing heat treatment.

In the accompanying drawings, Figure 1 is a front view illustrating oneform of crimping apparatus adapted to the practice of the presentinvention.

Figure 2 is a side elevational view of the ap paratus shown in Figure 1.

Figure 3 is a perspective view of a stack of sheets shown'in explodedrelationship to illustrate the material before treatment by this method.

Figure 4 is representative of a stack of sheets after passing throughthe crimper.

Figure 5 is a schematic plan view, showing the manner in which thesheets are advanced into and through the crimper preparatory tostacking. I

Figure 6 represents, in plan view, one method of stacking sheets inaccordance with the present invention.

Figure 7 is an elevational view of the end of the pack shown in Figure6.

Figure 8 is a view corresponding to Figure 7 after the pack has beenpassed through the crimping rolls.

Figure 9 is a view similar to Figures 7 and 8 showing the sheetsrepacked for the steam bluing operation.

Referring more particularly to thedrawings, the device illustrated inFigures 1 and 2 comprises a roll stand I having a pair of crimping rolls2 and 3 Journaled therein in bearings 4 and 5, respectively. The lowerroll 3 is arranged for revolution about a fixed axis by virtue of itsbearings 5 being rigidly retained in the roll stand I. The upper roll 2is adapted to be raised and lowered in relation to the bottom roll,which is accomplished by its bearings 4 being vertically adjustable inthe roll stand I by a screw-down device 6 actingln opposition to a leafspring I interposed between the upper bearings 4 and the lower bearings5 of the rolls. From this arrangement it will be understood that therolls are opened by backing-off the screw-down 8 to allow the leafspring 1 to lift the bearings 4 in relation to the bearings 5. The rollsare closed by actuating the screw-downs in an opposite direction tourgethe upper bearings 4 toward the lower bearings 5 against the tensionof the spring 1. Any suitable arrangement is, of course, permissible toachieve this end.

The crimping rolls are preferably driven. through an extension 8 of oneof the necks of the lower roll 3, by a motor 9 and'a reduction gear III,which latter is connected to the roll neck extension 8 by a drivecoupling l I. Suitable motor controls are conveniently placed as at I2to vary the operating speed of the motor, thus to adjust the effectivespeed of the rolls to the desired value.

The crimping rolls. 2 and 3 are designed to impart a very gradualreverse curvature to the sheets so as to avoid sharp bends or anydeformation that would tend permanently to mark the sheets, since theamount of offset need be but very slight to afford optimum bluingconditions as will presently appear. It is preferred that the verticaloffset of the rolls be not greater than /44" from hollow to crown andthe distance between crowns be sufiiciently great, such as in the orderof five or six inches, to provide a very gradual curvature.

Sheet material corresponding to that shown in Figure 3 is advancedthrough the crimping mechanism in the manner shown in Figure 5. Thesheets S are advanced through the crimping rolls, either singly or inpiles, preferably in av direction agreeing with their longitudinal axes.

As illustrated in this figure, they are introduced uniformly to coatboth surfaces ofeach sheet.

irrespective of its position in the pack.

Where the sheets are passed through the crimping rolls in stackedrelation, such as is desirable on gauges less than 24 gauge, a preferredarrangement for conducting this operation is shown in Figures 6 to 9inclusive. Two or more sheets, represented in these figures 81 So, So,S4,-

and 81, are stacked with their end marginal portions in substantialalignment and with their side marginal portions relatively displacedsidewise so as to dispose the sheets in slightly offset relation, asindicated in Figures 6 and 7. Such.

a pack is introducedto the crimping rolls endwise so as to dispose thecrimps longitudinally of the sheets. The result of this operation isillustrated in Figure 8 in which the sheets are treated as abovedescribed, are placed in an annealing receptacle and heated to thedesired temperature which will be relatively high if it is desired toanneal the sheets, but which need not exceed 1000 F. if it is intendedonly to blue the sheets. The bluing operation is usually conductedapproximately at 900 F. Thus, if the sheets have been annealed at 1200to 1300 F., it will be necessary to allowthe charge to cool to around900? F. before introducing steam into the annealingfurnace for effectingthe bluing op ration. Whether incident to an anneal or not, steam isintroduced into the annealing container at the prescribed temperatureand bathes the interior and exterior surfaces of the pack for theattainment of the blue oxide finish in a highly uniform manner.

The sheetsare thereafter cooled and removed from the annealingreceptacle, and may then be given one or two passes on a cold reductionmill depending on the temper and luster desired, or

desideratum here, therefore, is that the crimps extend in the directionof rolling, since they are shown in oil-set nesting relationship. Thesheets are then slid sideways, relative to each other until their sidemargins are in substantial alignment, as shown in Figure 9. Thisobviously dis- I ruptsthe nesting relationship of the crimps and.

provides a pack of the desired openness.

As has been said, the extent of the offset provided by the crimpingshould bev of a relatively slight order, preferably not to exceed /4'.and for optimum results, in the order of In this more easily obliteratedby a subsequent pass or two on a cold mill when disposed in thismanner.Another reason for this practice is to dispose the crimping in thatdirection in which the least number of crowns are impressed into thematerials By disposing the crimps longitudinally of eachsheet, thenumbero'f crowns thus'realized is necessarily less, by virtue of beingapplied across a lesser dimension of the sheet, than would be theconnection, it has been found that, where an exceedingly open pack isprovided by crimps of greater magnitude, such as would be represented bycommercial corrugating practice, the oxidizing .action thus allowed isso severe as to build up a heavy gray oxide throughout the more exposedareas of the sheets in the pack. Such a gray oxide not only presents anon-uniform contrast to the blued areas of the more sheltered portionsof the sheets, but is so brittle as to be completely cracked-off duringthe succeeding leveling operation so as to defeat the intended purpose.The gentle undulations or crimps, herein contemplated, afford no morethan the optimum openness of pack, thus to insure of the acquisi- Q tionof a uniform oxide blue coating throughout both surfaces of each sheet.therefore, that in addition to providing an open pack forinter-penetration of an oxidizing gas,

It will be seen,

inter-penetration of an active case were they to be applied crosswise ofthe sheet, and, thus, extend down its greatest dimension. Any slightmarking that might result from the crim ing operation is, because ofthis, minimized bi the preferred practice.

Obvio sly the extentof the crimping illustrated in Figure 4 has beengreatly exaggerated for purposes of illustration. Actually'the amount ofoffset provided by this crimpingneed be very slight in orderto beeffective in allowing the atmosphere through a stack of sheets as herecontemplated.

Since the apparatus and method for giving 'efl'ect to the novelrelationships herein disclosed may assume a variety of forms, it isintended that the herein disclosed embodiment ,be regarded asillustrative rather than restrictive. Therefore. it is not intended thatthe present invention be limited thereby other than as is necessitatedby the recitation of the appended claims.

I claim:

1. The method of treating metal sheets in stacks to insureinter-penetration of the atmosphere surrounding the stack, whichincludes the step of plastically deforming each of the sheets throughoutits cross-section so as to impart an undulatory characteristic to eachsheet to disrupt the planar disposition of its surfaces, stacking saidsheets so that corresponding undulations on adjacent sheetsareout ofregistry to avoid nest- 2. The method of steam bluing steel sheets whichincludes imparting a wavy characteristic thereto preparatory tostacking, stacking such sheets in a manner to avoid nesting thereof,heating said sheets in an enclosure, and admitting steam into saidenclosure to impart a blue oxide film uniformly over both surfaces ofeach sheet.

3. The method of steam bluing steel sheets which includes imparting awavy characteristic thereto preparatory to stacking, stacking the wavysheets to avoid nesting thereof, heating said sheets in an enclosure,and while heated, bathing them in steam by introducing steam into theenclosure to impart a blue oxide film to each surface of the severalsheets, removing the sheets from said enclosure, and working said sheetsto impart flatness, temper and luster.

4. The method of steam bluing steel sheets which includes crimping eachsheet preparatory to stacking, stacking said sheets to avoid the nestingthereof, heating said sheets in an enclosure, and, while at atemperature between 800? and 1000 F., introducing steam into saidenclosure to blue the sheets, removing the sheets, and working each oneto flatten and impart the requisite temper and finish thereto.

5. The method of steam bluing steel sheets which includes lightlycrimping a plurality of such sheets, stacking said sheets with thecrimps thereof in opposition to avoid nesting, enclosing said sheets inan annealing enclosure, annealing in stacks by an oxidizing atmosphereat elevated temperature, the improvement which includes, as apreparatory step, cold straining said sheets to warp them out of aplanar disposition, and stacking said sheets in non-nesting relationshipto provide an open pack.

8. In the art of uniformly bluing cold reduced steel sheets in stacks byan oxidizing atmosphere incident to an annealing thereof, theimprovement which includes passing each sheet through corrugatingrollers lightly to corrugate it so that the corrugations fall indifferent places in relation to the marginal portions of each sheet,stacking the sheets in congruent relation to provide an open pack,annealing said sheets, and, while within the annealing furnace, bathingthe pack in steam introduced into the furnace, cooling the sheets toroom temperature, and cold working each sheet to impart flatness, finishand temper.

9. In the art of bluing cold reduced steel sheets in stacks by anoxidizing atmosphere at elevated temperature, th improvement whichincludes, as a preparatory step, cold straining said sheets to warp themout of a planar disposition in a recurrent offset pattern, the extent ofthe offset not exceeding /4", and stacking said sheets in non-nestingrelationship to provide a pack of moderate openness.

10. In the art of bluing cold reduced steel vi sheets in stacks by anoxidizing atmosphere at said sheets, cooling said sheets from annealingtemperature within the enclosure to a temperature between 800 to 1000F., introducing steam into said enclosure to impart a blue oxidecoloration to both surfaces of each sheet substantially uniformly,cooling said sheets to room temperature, and working said sheets toimpart flatness, finish and temper.

6. The method of steam bluing steel sheets that have been cold reducedto gauge, which includes lightly crimping the cold reduced sheetspreparatory to stacking, stacking several of said sheets with thecorresponding crimps of adjacent sheets out of registry to provide anopen pack, annealing said sheets at a temperature in the neighborhood of1100" F., cooling the stack in the furnace down to about 900 F.,introducing steam into the furnace which permeates the pack and impartsa uniform blue oxide finish to both surfaces of each sheet thereof;thereafter, cold working said blued sheets to impart the desiredflatness, finish, and temper thereto.

7. In the art of bluing cold reduced steel sheets elevated temperature,the improvement which includes, as a preparatory step, cold strainingsaid sheets to crimp them in a manner to dispose the crimps so that thelongitudinal axes of the latter substantially agree with the directionin which the sheet will be subsequently rolled, limiting the depth ofcrimp to A," or less and stacking said sheet in non-nesting relationshipto provide a pack of moderate openness.

11. In the art of billing cold reducedv steel sheets in stacks by anoxidizing atmosphere at elevated temperature, the improvement whichincludes, as a preparatory step, stacking several sheets together withtheir edge portions out of substantial alignment and with theirremaining portions in overlapping relationship, passing such packendwise through crimping rolls so as to impress longitudinally extendingcrimps up on the pack, then re-assembling the sheets to bring theirmarginal portions into substantial alignment, thus to provide an openpack.

RAYMOND JOHNSON.

